Jupiter’s moon Europa was captured by the JunoCam instrument aboard NASA’s Juno spacecraft during the mission’s close flyby on September 29, 2022. The images show the fractures, ridges and bands that crisscross the surface of the moon. Credit: NASA/JPL-Caltech/SwRI /MSSS, Björn Jónsson (CC BY 3.0)
This black-and-white image of Europa’s surface was taken by the Stellar Reference Unit (SRU) aboard NASA’s Juno spacecraft during the flyby on September 29, 2022. The chaos element dubbed “the ‘Platypus’ is visible in the lower right corner. Credit: NASA/JPL-Caltech/SwRI
“True polar wandering occurs if Europa’s icy shell is decoupled from its rocky interior, resulting in high stress levels on the shell, leading to predictable fracture patterns,” said Candy Hansen, co -Juno researcher who leads planning for JunoCam at Planetary. Science Institute in Tucson, Arizona. “This is the first time these fracture patterns have been mapped in the Southern Hemisphere, suggesting that the effect of the true polar slip on the surface geology of Europa is more extensive than previously identified .”
High-resolution JunoCam imagery was also used to reclassify a once-important surface feature of the Europe map.
“Gwern Crater no longer exists,” Hansen said. “What was once thought to be a 13-mile-wide impact crater – one of Europe’s few documented impact craters – Gwern was revealed in JunoCam data to be a set of intersecting ridges which created an oval shadow.”
This annotated image of the surface of Europa taken by Juno’s SRU shows the location of a double ridge extending east-west (blue box) with possible plume patches and the chaos feature that l The team calls it “the platypus” (orange box). These features hint at current surface activity and the presence of subsurface liquid water on the icy Jovian moon. Credit: NASA/JPL-Caltech/SwRI
The platypus
Although Juno’s five images of Europa are all high resolution, the spacecraft’s black-and-white SRU image offers the most detail. Designed to detect faint stars for navigation purposes, the SRU is sensitive to low light. To avoid excessive illumination of the image, the team used the camera to photograph the nighttime part of Europa when it was only illuminated by sunlight scattered by Jupiter (a phenomenon called “Jupiter -shine”).
This innovative approach to imaging brought out complex surface features, revealing complex networks of transverse ridges and dark spots originating from potential water vapor plumes. One intriguing feature, which covers an area of 23 miles by 42 miles (37 kilometers by 67 kilometers), has been nicknamed by the team “the Platypus” because of its shape.
Characterized by chaotic terrain with mounds, prominent ridges, and dark reddish-brown materials, the Platypus is the youngest entity in its vicinity. Its northern “torso” and southern “beak” – connected by a fractured “neck” formation – interrupt the surrounding terrain with lumpy matrix material containing numerous blocks of ice measuring between 1 and 7 kilometers wide. The ridge formations collapse into the feature at the edges of the Platypus.
For the Juno team, these formations support the idea that Europa’s ice shell could give way in places where pockets of brackish water from the subterranean ocean are present below the surface.
About 50 kilometers north of Platypus is a set of double ridges flanked by dark spots similar to features found elsewhere on Europa and which scientists have assumed to be cryovolcanic plume deposits.
“These features hint at current surface activity and the presence of underground liquid water on Europa,” said Heidi Becker, SRU co-principal investigator at NASA’s Jet Propulsion Laboratory in Southern California, which manages also the mission. “The SRU image provides a high-quality reference for specific locations on NASA and ESA’s Europa Clipper mission (
” data-gt-translate-attributes=”({“attribute”:”data-cmtooltip”, “format”:”html”})” tabindex=”0″ role=”link”>European Space Agency‘s ) Juice missions can target looking for signs of change and brine.
Europa Clipper focuses on Europa, including studying whether the icy moon could provide conditions suitable for life. Its launch is planned for fall 2024 and its arrival on Jupiter in 2030. Juice (Jupiter Icy Moons Explorer) was launched on April 14, 2023. The ESA mission will reach Jupiter in July 2031 to study numerous targets (the three large, icy moons of Jupiter, as well as the fiery Io and smaller moons, as well as the planet’s atmosphere, magnetosphere and rings), with a particular focus on Ganymede.
Juno made its 61st close flyby of Jupiter on May 12. Its 62nd flyby of the gas giant, scheduled for June 13, includes a flyby of Io at an altitude of about 18,200 miles (29,300 kilometers).
The references:
“Juno’s JunoCam Images of Europa” by CJ Hansen, MA Ravine, PM Schenk, GC Collins, EJ Leonard, CB Phillips, MA Caplinger, F. Tosi, SJ Bolton and Björn Jónsson, March 21, 2024, The Journal of Planetary Science.
DOI: 10.3847/PSJ/ad24f4
Reference: “A complex region of Europa’s surface with evidence of recent activity revealed by Juno’s stellar reference unit” by Heidi N. Becker, Jonathan I. Lunine, Paul M. Schenk, Meghan M. Florence , Martin J. Brennan, Candice J. Hansen, Yasmina M. Martos, Scott J. Bolton and James W. Alexander, December 22, 2023, Geophysical Research Journal: Planets.
DOI: 10.1029/2023JE008105